How do I check my CIS deductions with HMRC?

Check your monthly CIS statements against your bank first, then call the CIS helpline on 0300 200 3210 to compare them with HMRC's records. Under Making Tax Digital, from April 2027, HMRC adds its figures to your return.

HMRC's record of your Construction Industry Scheme (CIS) deductions comes from your contractors. Every month, each contractor files a return listing what it paid each subcontractor and what it deducted. When you claim your deductions on your tax return, HMRC's manual says an automated comparison is made between what you claim and what your contractors reported. If the two do not match, your refund can be held up while HMRC asks questions.

Your options for checking

The helpline is open Monday to Friday, 8am to 6pm, and is closed on bank holidays. GOV.UK says it may ask security questions, so make sure your personal details are up to date in your personal tax account before you call. Have your UTR, your National Insurance number and your statements to hand.

What this means for you

Most mismatches are simple: a contractor typed the wrong UTR, put a payment in the wrong month, or used the wrong rate. These are easiest to fix while the contractor still has the paperwork, so check as you go rather than at the end of the year.

From 6 April 2027, if your income from self-employment and property before costs was over £30,000 in 2025-26, you join Making Tax Digital for Income Tax (MTD). GOV.UK says HMRC then adds your CIS deductions to your tax return, and you can find them in your software when you ask for a calculation, or in your HMRC online services account. You must check them before you submit. GOV.UK also says you cannot claim the refund in the MTD tax return itself. You request it through your HMRC online services account.

HMRC is also checking contractors' side. In its September 2026 Agent Update, HMRC said it would write in October 2026 to contractors whose monthly returns show errors such as wrong deduction rates or materials not recorded separately.

Steps if your figures do not match

1. Add up the gross pay and deductions on your statements for the tax year, 6 April to 5 April.
2. Match each statement to the payment in your bank account. A gap usually points to a wrong rate or a materials figure.
3. Call the CIS helpline and ask whether HMRC holds the payments and deductions you expect from each contractor.
4. If a contractor's figure is wrong, ask them to correct it. Contractors can correct their monthly returns using HMRC's CIS online service.
5. If the contractor will not or cannot, for example because it has closed, write to HMRC at PT Operations, BX9 1BX, with your UTR, the contractor's details and the dates you were paid.
6. If you and the contractor disagree about a deduction, ask HMRC for a ruling.
7. Claim on your tax return what was actually deducted, and keep the statements in case HMRC asks for evidence.

If you were charged 30%

If a contractor deducted 30% when you are registered, they may not have been able to verify you. GOV.UK says the details you give a contractor must match exactly the details you registered with, including your UTR and your legal business or trading name. Check your registration with the helpline, give the contractor the right details, and ask them to verify you again. The extra 10% is not lost. It is counted on your tax return like any other deduction.

Use the free MTD check to see whether Making Tax Digital applies to you from April 2027, and visit the trades section for more on CIS.